diff --git a/backend/services/deployment_history.py b/backend/services/deployment_history.py
index 0a5bd27..d9002fc 100644
--- a/backend/services/deployment_history.py
+++ b/backend/services/deployment_history.py
@@ -138,14 +138,26 @@ def get_deployment_history_data(
         p.id: p for p in db.query(Project).filter(Project.id.in_(proj_ids)).all()
     } if proj_ids else {}
 
+    # Resolve location names in one batch query (used by the Gantt view
+    # for per-bar tooltips).
+    from backend.models import MonitoringLocation
+    loc_ids = {a.location_id for a in assignments}
+    loc_name_map = {
+        l.id: l.name for l in db.query(MonitoringLocation).filter(
+            MonitoringLocation.id.in_(loc_ids)
+        ).all()
+    } if loc_ids else {}
+
     # Compute "active days per project" by walking each assignment and
     # adding every day in its [start, end] ∩ [first_date, last_date].
     # O(N_assignments × avg_window_days); for a typical fleet this is
     # bounded (hundreds of assignments × hundreds of days = manageable).
+    # Also collect raw per-assignment bar data for the Gantt view.
     project_active_days: dict[str, set[date]] = {}
     project_first_active: dict[str, date] = {}
     project_last_active:  dict[str, date] = {}
     project_assignment_count: dict[str, int] = {}
+    project_bars: dict[str, list[dict]] = {}
     distinct_units: set[str] = set()
 
     for a in assignments:
@@ -169,6 +181,20 @@ def get_deployment_history_data(
         if prev_last is None or end > prev_last:
             project_last_active[a.project_id] = end
 
+        # Per-assignment bar data — used by the Gantt view's renderer.
+        # `is_active` reflects whether the assignment_until was still NULL
+        # at fetch time (open-ended deployment); the clipped `end` here
+        # is just for visual bar drawing.
+        project_bars.setdefault(a.project_id, []).append({
+            "unit_id":       a.unit_id,
+            "location_id":   a.location_id,
+            "location_name": loc_name_map.get(a.location_id, "(unknown location)"),
+            "start":         start.isoformat(),
+            "end":           end.isoformat(),
+            "is_active":     a.assigned_until is None,
+            "source":        a.source,
+        })
+
     # Build the projects array (sorted by first_active ascending so the
     # legend reads in deployment-order).
     projects_data = []
@@ -186,6 +212,7 @@ def get_deployment_history_data(
                 "assignment_count": project_assignment_count.get(pid, 0),
                 "first_active": project_first_active[pid].isoformat() if pid in project_first_active else None,
                 "last_active":  project_last_active[pid].isoformat()  if pid in project_last_active  else None,
+                "bars":         project_bars.get(pid, []),
             })
             continue
         projects_data.append({
@@ -197,6 +224,7 @@ def get_deployment_history_data(
             "assignment_count": project_assignment_count.get(pid, 0),
             "first_active":     project_first_active[pid].isoformat() if pid in project_first_active else None,
             "last_active":      project_last_active[pid].isoformat()  if pid in project_last_active  else None,
+            "bars":             project_bars.get(pid, []),
         })
 
     projects_data.sort(key=lambda p: (p["first_active"] or "9999", p["name"]))
diff --git a/templates/admin/deployment_history.html b/templates/admin/deployment_history.html
index b3fdf48..e77d0b0 100644
--- a/templates/admin/deployment_history.html
+++ b/templates/admin/deployment_history.html
@@ -97,6 +97,18 @@
     </div>
 </div>
 
+<!-- View tabs: Calendar | Gantt -->
+<div class="flex rounded-lg bg-gray-100 dark:bg-gray-700 p-1 mb-6 w-fit">
+    <button id="dh-tab-calendar" onclick="switchDhView('calendar')"
+            class="px-4 py-2 rounded-md text-sm font-medium transition-colors bg-white dark:bg-slate-600 text-gray-900 dark:text-white shadow">
+        Calendar
+    </button>
+    <button id="dh-tab-gantt" onclick="switchDhView('gantt')"
+            class="px-4 py-2 rounded-md text-sm font-medium transition-colors text-gray-600 dark:text-gray-300 hover:text-gray-900 dark:hover:text-white">
+        Gantt
+    </button>
+</div>
+
 <!-- KPI strip -->
 <div class="flex flex-wrap items-center gap-4 mb-6">
     <div class="flex items-center gap-3 text-sm bg-white dark:bg-slate-800 rounded-lg px-4 py-2 shadow">
@@ -124,6 +136,9 @@
     {% endif %}
 </div>
 
+<!-- ─── Calendar view ─── -->
+<div id="dh-view-calendar">
+
 <!-- Calendar grid -->
 {% if calendar.projects %}
 <div class="dh-calendar-grid mb-6">
@@ -211,6 +226,52 @@
 </div>
 {% endif %}
 
+</div>  {# /#dh-view-calendar #}
+
+<!-- ─── Gantt view ─── -->
+<div id="dh-view-gantt" class="hidden">
+{% if calendar.projects %}
+    <div class="bg-white dark:bg-slate-800 rounded-xl shadow-lg p-4 mb-6 overflow-x-auto">
+        <p class="text-xs text-gray-500 dark:text-gray-400 mb-3">
+            One row per project.  Each bar is one assignment window (unit at a location).
+            Hover for details, click to open the project.
+            Active deployments end at "now" with a small white tip.
+        </p>
+        <svg id="dh-gantt-svg" preserveAspectRatio="none"
+             style="width: 100%; min-width: 800px;"></svg>
+    </div>
+
+    <!-- Same nav as calendar view, repeated here so the Gantt view has its own. -->
+    <div class="flex items-center justify-center gap-3 mb-8">
+        <a href="/tools/deployment-history?year={{ prev_year }}&month={{ prev_month }}#gantt"
+           class="px-3 py-2 rounded-lg bg-gray-100 dark:bg-gray-700 hover:bg-gray-200 dark:hover:bg-gray-600 text-gray-700 dark:text-gray-300"
+           title="Previous month">
+            <svg class="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M15 19l-7-7 7-7"/>
+            </svg>
+        </a>
+        <span class="text-lg font-bold text-gray-900 dark:text-white px-3">
+            {{ calendar.months[0].short_name }} '{{ calendar.months[0].year_short }} – {{ calendar.months[11].short_name }} '{{ calendar.months[11].year_short }}
+        </span>
+        <a href="/tools/deployment-history?year={{ next_year }}&month={{ next_month }}#gantt"
+           class="px-3 py-2 rounded-lg bg-gray-100 dark:bg-gray-700 hover:bg-gray-200 dark:hover:bg-gray-600 text-gray-700 dark:text-gray-300"
+           title="Next month">
+            <svg class="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7"/>
+            </svg>
+        </a>
+        <a href="/tools/deployment-history#gantt"
+           class="ml-2 px-4 py-2 rounded-lg bg-seismo-orange text-white hover:bg-orange-600">
+            Recent
+        </a>
+    </div>
+{% else %}
+    <div class="bg-white dark:bg-slate-800 rounded-xl shadow-lg p-8 text-center text-gray-500 dark:text-gray-400">
+        <p class="text-sm">No deployments in this window.</p>
+    </div>
+{% endif %}
+</div>  {# /#dh-view-gantt #}
+
 <!-- Day-detail side panel -->
 <div id="dh-day-panel-backdrop"
      class="fixed inset-0 bg-black/30 z-40 hidden transition-opacity"
@@ -342,5 +403,148 @@ function closeDhDayPanel() {
 document.addEventListener('keydown', (e) => {
     if (e.key === 'Escape') closeDhDayPanel();
 });
+
+// ── Tab switcher ────────────────────────────────────────────────────
+function switchDhView(which) {
+    const cal   = document.getElementById('dh-view-calendar');
+    const gantt = document.getElementById('dh-view-gantt');
+    const btnC  = document.getElementById('dh-tab-calendar');
+    const btnG  = document.getElementById('dh-tab-gantt');
+    const activeCls = ['bg-white', 'dark:bg-slate-600', 'text-gray-900', 'dark:text-white', 'shadow'];
+    const dormantCls = ['text-gray-600', 'dark:text-gray-300', 'hover:text-gray-900', 'dark:hover:text-white'];
+    if (which === 'gantt') {
+        cal.classList.add('hidden');
+        gantt.classList.remove('hidden');
+        btnG.classList.add(...activeCls);   btnG.classList.remove(...dormantCls);
+        btnC.classList.remove(...activeCls); btnC.classList.add(...dormantCls);
+        if (window.location.hash !== '#gantt') {
+            history.replaceState(null, '', window.location.pathname + window.location.search + '#gantt');
+        }
+        renderDhGantt();
+    } else {
+        gantt.classList.add('hidden');
+        cal.classList.remove('hidden');
+        btnC.classList.add(...activeCls);    btnC.classList.remove(...dormantCls);
+        btnG.classList.remove(...activeCls); btnG.classList.add(...dormantCls);
+        if (window.location.hash === '#gantt') {
+            history.replaceState(null, '', window.location.pathname + window.location.search);
+        }
+    }
+}
+
+// Land on the Gantt view if URL hash is #gantt.
+if (window.location.hash === '#gantt') {
+    document.addEventListener('DOMContentLoaded', () => switchDhView('gantt'));
+}
+
+// ── Gantt renderer ──────────────────────────────────────────────────
+// Server-rendered data: per-project list with each project's bars
+// (assignment windows clipped to the visible window).
+const _dhProjects = {{ calendar.projects | tojson }};
+const _dhWindowStart = {{ calendar.window.first_date | tojson }};
+const _dhWindowEnd   = {{ calendar.window.last_date  | tojson }};
+
+let _ganttRendered = false;
+function renderDhGantt() {
+    if (_ganttRendered) return;   // build once; data doesn't change after page load
+    _ganttRendered = true;
+    const svg = document.getElementById('dh-gantt-svg');
+    if (!svg) return;
+    if (!_dhProjects || _dhProjects.length === 0) {
+        svg.innerHTML = '';
+        return;
+    }
+
+    const isDark = document.documentElement.classList.contains('dark');
+    const labelColor = isDark ? '#9ca3af' : '#6b7280';
+    const gridColor  = isDark ? '#374151' : '#e5e7eb';
+    const rowAltBg   = isDark ? '#1e293b' : '#f9fafb';
+    const todayColor = '#f48b1c';
+
+    // Geometry.  The Gantt SVG has a left "labels" gutter and a right
+    // time-axis area.  Width is fluid (matches container); height grows
+    // with the number of project rows.
+    const containerW = svg.parentElement.clientWidth || 1000;
+    const width      = Math.max(containerW, 800);
+    const labelW     = 220;
+    const padTop     = 36;       // room for month labels above
+    const padBottom  = 16;
+    const rowH       = 36;
+    const barH       = 18;
+    const height     = padTop + padBottom + _dhProjects.length * rowH;
+
+    const usableW = width - labelW - 8;
+
+    const tStart = new Date(_dhWindowStart + 'T00:00:00Z').getTime();
+    const tEnd   = new Date(_dhWindowEnd   + 'T23:59:59Z').getTime();
+    const tRange = tEnd - tStart;
+    const xFor = (d) => {
+        const ms = (typeof d === 'string') ? new Date(d + 'T00:00:00Z').getTime() : d;
+        return labelW + Math.max(0, Math.min(usableW, (ms - tStart) / tRange * usableW));
+    };
+
+    // Month gridlines + month labels along the top.
+    // Walk every 1st-of-month inside the window.
+    const monthsParts = [];
+    const cursor = new Date(_dhWindowStart + 'T00:00:00Z');
+    cursor.setUTCDate(1);
+    while (cursor.getTime() <= tEnd) {
+        const x = xFor(cursor);
+        const label = cursor.toLocaleDateString('en-US', { month: 'short', year: '2-digit', timeZone: 'UTC' });
+        monthsParts.push(`<line x1="${x}" y1="${padTop}" x2="${x}" y2="${height - padBottom}" stroke="${gridColor}" stroke-width="1"/>`);
+        monthsParts.push(`<text x="${x + 2}" y="${padTop - 6}" font-size="10" fill="${labelColor}" font-family="system-ui,sans-serif">${label}</text>`);
+        cursor.setUTCMonth(cursor.getUTCMonth() + 1);
+    }
+
+    // Today marker.
+    const now = Date.now();
+    let todayMarker = '';
+    if (now >= tStart && now <= tEnd) {
+        const x = xFor(now);
+        todayMarker = `<line x1="${x}" y1="${padTop}" x2="${x}" y2="${height - padBottom}" stroke="${todayColor}" stroke-width="2" stroke-dasharray="3 2" opacity="0.85"/>
+            <text x="${x + 3}" y="${padTop - 20}" font-size="9" fill="${todayColor}" font-family="system-ui,sans-serif">today</text>`;
+    }
+
+    // Build rows.
+    const rowParts = [];
+    _dhProjects.forEach((proj, idx) => {
+        const y = padTop + idx * rowH;
+        // Alternating row background.
+        if (idx % 2 === 1) {
+            rowParts.push(`<rect x="0" y="${y}" width="${width}" height="${rowH}" fill="${rowAltBg}"/>`);
+        }
+        // Project label (clipped to gutter, clickable).
+        const labelText = proj.name.length > 28 ? proj.name.slice(0, 26) + '…' : proj.name;
+        rowParts.push(`<a href="/projects/${_dhEsc(proj.id)}" target="_top">
+            <rect x="0" y="${y}" width="${labelW}" height="${rowH}" fill="transparent"/>
+            <circle cx="14" cy="${y + rowH / 2}" r="4" fill="${proj.color}"/>
+            <text x="24" y="${y + rowH / 2 + 4}" font-size="12" fill="${labelColor}"
+                  font-family="system-ui,sans-serif"
+                  title="${_dhEsc(proj.name)}">
+                ${_dhEsc(labelText)}
+            </text>
+        </a>`);
+        // Bars for each assignment in this project.
+        for (const bar of (proj.bars || [])) {
+            const x1 = xFor(bar.start);
+            const x2 = xFor(bar.end);
+            const barW = Math.max(x2 - x1, 2);
+            const by = y + (rowH - barH) / 2;
+            const tip = `${bar.unit_id} @ ${bar.location_name}\n${bar.start} → ${bar.is_active ? 'present' : bar.end}`;
+            rowParts.push(`<g style="cursor: pointer;">
+                <title>${_dhEsc(tip)}</title>
+                <rect x="${x1}" y="${by}" width="${barW}" height="${barH}"
+                      rx="3"
+                      fill="${proj.color}" opacity="${bar.is_active ? 1.0 : 0.75}"
+                      ${bar.source === 'metadata_backfill' ? 'stroke="#3b82f6" stroke-width="1.5"' : ''}/>
+                ${bar.is_active ? `<rect x="${x2 - 3}" y="${by}" width="3" height="${barH}" fill="#ffffff" opacity="0.8"/>` : ''}
+            </g>`);
+        }
+    });
+
+    svg.setAttribute('viewBox', `0 0 ${width} ${height}`);
+    svg.setAttribute('height', height);
+    svg.innerHTML = monthsParts.join('') + rowParts.join('') + todayMarker;
+}
 </script>
 {% endblock %}